Scheduled pruning / optimizing attachments to save disk space

What are the best methods and practices to conduct regular , preferably automated and scheduled POSTS ATTACHMENTS PRUNING and or OPTIMIZATION.
Lets say a scheduled task that does either of or all of the following:
1- Deleting all post attachments after a certain period of time.
2- Optimizing by merging those attachments of duplicate file names, lets say saving those types only once – in the profile of the user that 1st posted them- then their other occurrences would be just linking to the 1st instance of that attachment.
3- Moving older attachments –lets say every six months – to a given directory then applying some sort of compression.

I find attachment pruning and optimization a core forum runners concern and I hope vBulletin’s technical team would consider marking this topic as a sticky , or starting a similar one as a sticky and posting the link here , so to build up a compilation of useful practices and techniques that fully utilizes the robust technologies in vBulletin 5, some which may not yet been discovered by many forum administrators.

Also any suggestions of paid or free modifications and plugins are welcome